Automatic grab



Aun 12, v1947. A. T. DEILY AUTOMATIC GRAB Filed Nov. 4, 1944 2Sheets-sneet 1 A. T. DEILY AUTOMATIC' GRAB Aug. 12, 1947.

2 Sheets-Sheet 2 Filed NOV. 4, 1944 afa :ma -Tui r wm,

l @fron/ver Patented Aug. 12, 1947 AUTOMATIC GRAB Arthur T. Deily,Pittsburgh, Pa., assignor to Aluminum Company of America, Pittsburgh,Pa., a corporation of Pennsylvania Application November 4, 1944, SerialNo. 561,949

3 Claims.

This invention relates to lifting device of the grab or tong type suchas is used for engaging and moving or otherwise handling articles ofani7 configuration but particularly those which are roughly square oroblong in configuration such as trays, baskets, racks, pieces of timber,large metal ingot and the like.

The object of the invention is to provide a lifting device which may bemoved from one place to another by means of a crane or hoist and whichis more or less automatic in the sense that it will, under propermanipulation, engage and disengage the article to be lifted withoutmanual help.

The attached drawings illustrate in several views a lifting deviceembodying the principles of the invention, said views being as follows:

Fig. 1 is a top view;

Fig. 2 is a view in side elevation;

Fig. 3 a cross sectional view taken on the line 3-3 of Fig. 1 in thedirection indicated by the arrows;

Fig. 4 a top view taken on the line 4 4 of Fig. 3 in the directionindicated by the arrows; and

Fig. 5 a cross sectional view taken at the line 5--5 of Fig, 2 in thedirection indicated by the arrows.

Referring to these drawings, in which like numerals designate likeparts, the lifting device or grab consists of three main parts: asuitable supn porting frame I, which is preferably square or rectangularin plan and which is adapted to carry all of the cooperating parts ofthe lifting device, and two side frames which depend from the supportingframe I and are pivoted to said frame i for swinging motion. Each of theside frames forms, in total, a work engaging or tong or grab arm andconsists of a plurality of spaced members 2 which are pivotallyconnected to the frame I and which at their other end are joinedtogether by a channel frame member 3 which not only joins the members 2into a unit to form the side frame or arm but likewise forms a ledgeadapted to support the object grasped by the arms as they are swung intoregister with said object. In order that the members 2, and thereforethe arm of which they are a part, may swing freely, each such member isprovided with an inwardly projecting end piece 4 adapted to be mounted,as shown, on shafts 5 and keyed to said shafts. Shafts y5 are mounted-on the top of the frame I and are there suitably supported in bearings6. The members .2 which lie at the extremities of each side arm areprovided with an upward extension 1, which in turn bears a bolt 8 onwhich is mounted the cross piece 9. Springs I3 are provided at the topof the frame I at each end thereof and one endof each spring is Xedlyattached to uprights II carried in the center of said frame I, the otherend of the springs being attached to the cross pieces 9. Springs IB aretensioned as by adjustment of the cross-pieces 9 on the bolts 8 so thatthey tend to pull the crosspieces toward the lcenter of the frame I andthus swing the side arms outwardly.

The device thus described is adapted to be lifted by a hoist or cranewhich attaches (at two longitudinally spaced points in the specificdevice shown) to the ring I2, which ring in turn is linked to theswinging arms of the lifting device by the flexible chains I3. It willbe apparent that either a single or multiple point suspension may beused and that in a lifting device of the type illustrated in thedrawings a balanced two-point suspension is to be preferred. Regardlessof the number of points of suspension, the ring I2 and flexible chainsI3 are located above and attached to one end of the end pieces 4 ofopposite members 2, and at the place where these points of suspensionare located the end piece 4 is so shaped as to form a lever or crankwhereby force applied upwardly through ring I2 and chains I3 will tendto rotate the members 2 on the shafts 5 and thus close the side armsagainst the action of springs I.

Thus it will be observed that if the lifting device rests, for instance,on the floor with one of its side arms on either side of the object tobe lifted, said side arms will be swung into the outward positionindicated by the dotted line in Fig. 3 and lwill be maintained in thisposition by the normal force of the springs ill, which tend to rotatethe members 2 outwardly. If, however, force is applied through ring I2tending to raise the lifting device upwardly, that force, if nototherwise opposed, will tend to rotate the side arms inwardly to thefull line position' shown in Fig. 3, whereupon the tray I5 or otherarticle which lies between those arms will be grasped by those arms andseated thereon in the manner shown at Fig. 3. Further lifting forceapplied through the ring by the hoist or crane to which they areattached will maintain the side arms in a work grasping position whilethe article or tray is moved from one spot to another, but when thelifting device and its contained tray is again placed on a floor andtension from the hoist is eliminated and chains I3 are loosened, thenormal action of the springs Il) will automatically disengage the sidearms from the tray and return them to the position indicated in dottedline at Fig. 3. In orderthat the varied positions of the side arms,which are automatically assumed under the conditions above outlined, maybe maintained at proper intervals, there is associated with at least oneset of corresponding members 2 of each side arm a ratchet mechanism,which is best shown at Figs. 3 and 4. This ratchet mechanism comprisesrastar wheel I keyed to a shaft I'I, which shaft is Vjournaled in bearingsI3 carried by transverse members of the supporting frame I. Said starwheel bears projections I9, equally spaced circumferentially, and a likenumber of recesses 2i! between said projections. Pivotally connected tothe opposed members 2 are the plunger rods 2i, which are positioned inspace by means of apertures in the cross members 29 and the frame I,through which apertures the plunger rods pass. If desired, each rod maycarry at its inner end an adjustable nose piece 22 for such lengthadjustments as are necessary. The rods 2! are so aligned that theirinner ends Vare adapted to register with either the projections i or therecesses 2li of the star Wheel IS, depending upon the position of thestar wheel at any given moment. The star wheel I6 is rotated to bringits projections or recesses into or out of register with the ends of theplunger rods 2l by means vof the ratchet wheel 23 which is keyed to ahub extensionv of said star wheel. Pawl 2li is mounted Yto preventrotaton of ratchet wheel .23 in one direction. Movement in the otherdirection of the ratchet wheel is imparted by lever 25 mounted on shaftl'l which lever is adapted to be raised by means of the flexibleconnection 26 between the lever and lifting ring I2. The lever 25carries a spring pressed pawl 2 vwhich is so mounted on said lever thatlifting of the lever brings the ,pawl 2? into position to engage a toothon the ratchet wheel. Spring 28 is mounted to constantly pull lever 25downwardly so that when the lifting device is placed upon la floor orsupport and the -exible chains I3 and the lever operating chain 26become slack the spring 28 operates the lever 25 pulling the lever andits attached pawl 2l downwardly, thereby indexing the ratchet star wheeli .to the next position.

The lifting device as illustrated in the drawings has been particularlydesigned for .the lifting of .stacked trays such as those shown at I5and therefore includes refinements not necessary to the operation ofkthe device in its broader applications but particulariyuseful in thatspecific application. Included among such reiinements are means forinsuring that, when the lifting `device l'is placed over the stackedtrays and its .side arms closed, the arms as they are swinging togetherwill register with the spaces sii provided in the tray for the entryofthe arm ends (see Figs. 3 and 5'). Referring to Figs. 2 and 5, thismeans consists of stop arms 3l pivoted at their upper ends in extensions32 vof the frame i and adapted to be swung inwardly so that their endscontact -the top of the stacked tray I5 and prevent the lifting devicefrom being lowered vbeyond a pre- .determined point. To hold said stoparms .3i in vtheir inwardly swung .position removable pins 2,3 aresuitably provided at a proper point in the lframe extensions 32. Anotherrefinement are the wheels ,34 mounted for free turning movement onshafts at the bottom of Aeach member 2 of `each side arm. Thesewheelsmerely provide ro- ,tating guideswhen the lifting .device'bearingthe 4 trays is lowered between conning walls such as the walls of animmersion tank.

The operation of the specic device will now be described. Assuming thatthe crane operator desires to lift a set of stacked trays I5 and thatthe lifting device is resting on the floor with its side arms openedoutwardly by the normal force of the springs l0, the rrst step of theoperator is to set the star wheel I6 so that its projections I9 are inregister with ends 22'of plunger rod 2 If. So positioned the star wheelI6 will prevent the side arms from closing as the lifting device israised from the floor by the crane and lowered over the trays I5because, although the force exerted by the lifting movement through theY chains I3 would tend to pull the side arms inwardly against the actionof the springs I0, the side arms are held in their outward position bythe plunger rods 2l and the pawl 24 operates to hold the ratchet wheel23 stationary. However when the lifting device is lowered by theoperator over the stacked trays and comes to rest thereon as stop arms3l contact the top of the upper tray (as shown'in Fig. 5) and thechainsV I3 and 2e again become slack the spring 28'pulls lever 25 andits spring actuated pawl 21 downward thus moving ratchet wheel 23 andindexing star wheel iE so that recesses 20 register with end 22 of theplunger rods. Therefore, the crane operator by taking up the slack ofchains I3, and thereby beginning the raising of the lifting device,immediately pulls the side arms inwardly into contact with the stackedtrays (as shown in Fig. 3) the plunger arms 2 I allowing this movementby pressing into the recesses 20 of the star wheel I6, and the trays maybe lifted Ato another spot. When the trays are to be released the craneoperator merely lowers the lifting device to the iloor whereupon theslackening of the chainV 26 againallows the spring 23 to functionindexing the star wheel I5 to where its projections I9 again preventclosing of the side arms as the lifting device is raised from itsposition around said trays.

Having thus described my invention, I claim:

1. in a lifting device, in combination, a frame, depending side armspivotally mounted on said frame, means cooperating with said arms tonormally and yieldingly force said arms out of lifting position, meansfor suspending the lifting device from the mechanism for lowering andraising said device, said suspension means being linked to said arms tonormally .force the arms into lifting position during suspension, aratchet mechanism, means cooperating with said ratchet to periodicallyprevent movement of said arms into lifting position and a linkconnecting the said ratchet mechanism and said suspension means andoperable .by the suspension operation to cause timed movement of theratchet 4mechanism with .respect thereto.

2. AIn a lifting device, in combination, a frame, depending sidey armspivotallymounted on said frame, crank extensions Aon said arms to swingthem toward each other into closed position when v,lifting force `is.applied Vto said extensions, spring means forswinging saidarms awayfrom each other into open position when said lifting force is removed,suspension means connected to said extensions Aby which said vdevice isattachable to a raising and lowering mechanism@ `pawl and ratchetmechanism carried bysaid framean operating Vmember therefor, a springfor actuating said member inthe ratchet operating direction, vvmeansactuated by :said lratchet lmechanism to alternately ,permit andyprevent movement of said arms into closed position, and meansconnecting said suspension means and said operating member for movingsaid member against its said actuating spring upon application oflifting force to said suspension means, to condition said member forsubsequently actuating said ratchet mechanism upon removal of thelifting force from said suspension means,

3. In a lifting device, in combination, a frame, depending side armspivotally mounted on said frame, means cooperating with said arms tonormally and yieldingly force the arms out of lifting position,suspension means adapted to suspend the lifting device during each cycleof raising and lowering said device and linked to said arms to normallyforce the arms into lifting position during suspension, an indexingmechanism adapted to prevent movement of said arms into lifting positionduring suspension in alternate cycles and means directly linking saidindexing mechanism to said suspension means and operable under theapplication of raising force by said 6 suspension means to induce anindexing action at the completion of the raising and lowering cycle,whereby the indexing mechanism is positioned to prevent movement of theylifting arms into lifting position during alternate cycles.

ARTHUR T. DEILY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

